Glenn Shafer (born November 21, 1946) is an American mathematician and statistician. He is the co-creator of Dempster–Shafer theory. He is a University Professor and Board of Governors Professor at Rutgers University.

Shafer grew up on a farm near Caney, Kansas. He received a bachelor's degree in mathematics from Princeton University, then entered the Peace Corps, serving in Afghanistan. He returned to Princeton, earning a PhD in mathematical statistics in 1973 under Geoffrey Watson.^[1][2]

He taught at Princeton and the University of Kansas, joining the faculty of Rutgers Business School – Newark and New Brunswick in 1992. From 2011 to 2014 he served as dean of the school.

During the 1970s and 1980s he expanded a theory first introduced by Arthur P. Dempster to create Dempster–Shafer theory, also described as the theory of belief functions or evidence theory. It is a general framework for reasoning with uncertainty, allowing one to combine evidence from different sources and arrive at a degree of belief (represented by a mathematical object called belief function) that takes into account all the available evidence.^[3] The theory and its extensions have been of particular interest to the artificial intelligence community.^[4]

More recently he worked with Vladimir Vovk to develop a game-theoretic framework for probability. That work produced a 2001 book, Probability and Finance: It's Only a Game! A joint research group between Rutgers and Royal Holloway, University of London has produced more than 50 working papers on the subject.^[5]

He is designated as a Board of Governors Professor at Rutgers. The University of Prague recognized him with an honorary doctorate. He has been a Fulbright Fellow and a Guggenheim Fellow.^[1] He was elected a Fellow of the Association for the Advancement of Artificial Intelligence in 1992.^[8]

He is married to retired Princeton professor and artist Nell Irvin Painter.